HSC Survey Results

German Bank Survey # 6 Results from 20/10/2024

Survey Details

6 commercial purse seiners conducted this fishing survey on 20/10/2024 starting at 19:00:00.

All vessels ran two transects in the German Bank box and two transect in the Seal Island Box.

There was a plankton tow and replicate conducted and CTD cast by Lady Janice II.

No tags were applied during this survey.

Samples were obtained for target strength estimation.

Acoustic Equipment

Each vessel was equipped with a Simrad ES38-18/200-18C combi (2-in-1) transducer prior to the survey that contains a 38kHz split beam and 200 kHz single beam transducer. Data was logged to the computer hard-drive for post-processing. All participating boats were calibrated on 38kHz before the survey.

Survey Results

Main Results

The results are subject to change as DFO will re-evaluate data editing, area estimation and apply a target strength.

Preliminary biomass prediction for German Bank using standardized parallel transects is 5,151mt, and with turnover applied 4,071mt. The preliminary biomass estimate for Seal Island is 2,928mt.

Transect Details

Table 1: Transect Details
Vessel Transect # Date/Time Start Date/Time End Start Lon Start Lat End Lon End Lat Location Distance (km) Speed
BP T01 2024-10-20 18:18:35 2024-10-20 20:38:06 -66.470 43.564 -66.470 43.236 GB 36.48 8.47
BP T02 2024-10-20 21:20:44 2024-10-20 23:27:42 -66.322 43.236 -66.322 43.562 GB 36.33 9.27
BP T03 2024-10-21 00:07:56 2024-10-21 01:59:22 -66.221 43.505 -66.220 43.257 GB 27.62 8.03
BP T04 2024-10-21 02:16:39 2024-10-21 03:47:17 -66.162 43.253 -66.171 43.505 GB 28.20 10.08
FM T01 2024-10-20 19:40:06 2024-10-20 22:06:22 -66.425 43.562 -66.424 43.234 GB 38.71 8.57
FM T02 2024-10-20 22:48:59 2024-10-21 01:02:53 -66.286 43.235 -66.286 43.565 GB 37.96 9.19
FM T03 2024-10-21 01:46:42 2024-10-21 03:40:01 -66.202 43.505 -66.201 43.249 GB 29.88 8.54
FM T04 2024-10-21 03:58:17 2024-10-21 05:48:00 -66.144 43.250 -66.147 43.505 GB 29.50 8.71
LB T01 2024-10-20 18:39:16 2024-10-20 20:57:49 -66.493 43.567 -66.493 43.232 GB 38.27 8.95
LB T02 2024-10-20 21:44:17 2024-10-20 23:57:14 -66.355 43.236 -66.356 43.566 GB 38.15 9.30
LB T03 2024-10-21 00:54:19 2024-10-21 02:59:00 -66.232 43.507 -66.229 43.250 GB 29.88 7.76
LB T04 2024-10-21 03:15:55 2024-10-21 05:15:40 -66.172 43.249 -66.174 43.506 GB 29.74 8.05
LJ T01 2024-10-20 18:41:12 2024-10-20 21:08:35 -66.378 43.568 -66.378 43.234 GB 37.12 8.16
LJ T02 2024-10-20 21:48:50 2024-10-21 00:12:39 -66.240 43.233 -66.239 43.568 GB 37.22 8.38
LJ T03 2024-10-21 00:51:28 2024-10-21 02:46:04 -66.183 43.503 -66.182 43.246 GB 28.62 8.09
LJ T04 2024-10-21 03:01:29 2024-10-21 04:53:54 -66.125 43.245 -66.125 43.500 GB 28.53 8.22
LM T01 2024-10-20 18:29:03 2024-10-20 21:00:23 -66.400 43.574 -66.402 43.233 GB 38.80 8.31
LM T02 2024-10-20 21:38:07 2024-10-20 23:59:02 -66.263 43.234 -66.262 43.567 GB 37.86 8.70
LM T03 2024-10-21 00:35:17 2024-10-21 02:22:14 -66.193 43.504 -66.192 43.250 GB 28.86 8.74
LM T04 2024-10-21 02:37:14 2024-10-21 04:28:41 -66.133 43.249 -66.135 43.503 GB 28.98 8.42
MS T01 2024-10-20 18:16:27 2024-10-20 20:51:00 -66.447 43.566 -66.448 43.234 GB 39.93 8.37
MS T02 2024-10-20 21:34:32 2024-10-20 23:48:45 -66.308 43.234 -66.309 43.564 GB 39.32 9.49
MS T03 2024-10-21 00:36:51 2024-10-21 02:35:32 -66.211 43.502 -66.211 43.248 GB 30.61 8.36
MS T04 2024-10-21 02:52:52 2024-10-21 04:43:10 -66.154 43.249 -66.152 43.501 GB 31.02 9.11

Survey Summary

Table 2: Acoustic Survey Results
Vessel Transect No.  Target Strength (db/kg) Mean Sa (/m2) Biomass Density (kg/m2)
FM T03 -35.5 -51.840 0.023
FM T04 -35.5 -53.742 0.015
MS T03 -35.5 -53.868 0.015
LJ T03 -35.5 -54.750 0.012
LM T02 -35.5 -55.286 0.011
LB T04 -35.5 -55.343 0.010
BP T03 -35.5 -55.447 0.010
FM T02 -35.5 -55.461 0.010
MS T01 -35.5 -55.612 0.010
FM T01 -35.5 -55.929 0.009
MS T04 -35.5 -56.457 0.008
BP T04 -35.5 -56.684 0.008
LB T03 -35.5 -56.692 0.008
LB T01 -35.5 -57.373 0.006
LJ T02 -35.5 -57.856 0.006
LJ T04 -35.5 -58.056 0.006
LB T02 -35.5 -58.222 0.005
MS T02 -35.5 -58.810 0.005
BP T02 -35.5 -59.088 0.004
LM T03 -35.5 -59.412 0.004
LM T04 -35.5 -59.760 0.004
BP T01 -35.5 -60.851 0.003
LJ T01 -35.5 -61.006 0.003
LM T01 -35.5 -61.327 0.003
Note:
Transects are listed from greatest to least backscatter.
Table 3: Survey Summary Table
Layer Target Strength Area (km2) Mean Sa Density (kg/m2) Biomass (tons) Percent Area Percent Biomass Standard Error (tons) Standard Error (%)
German Bank -35.5 826 -57.5514 0.0062 5,151.497 74.2 63.8 705.15 13.69
Seal Island -35.5 287 -55.4135 0.0101 2,927.767 25.8 36.2 456.27 15.58

Greatest Biomass Densities

A snip from the transect with the greatest biomass density (kg/m2)

A snip from the transect with the greatest biomass density (kg/m2)

The single point with the largest biomass density (kg/m2) was recorded by LJ, at the following location:

The transect with the greatest average biomass density (kg/m2) was recorded by FM, at the following location:

Annual Summaries

This table does not include the biomass from adhoc surveys.

Table 4: Annual Comparison Table
Current Year
Previous Year
Ground Survey Number Survey Date HSC Estimate HSC Turnover Adjusted Survey Date HSC Estimate HSC Turnover Adjusted DFO Estimate DFO Turnover Adjusted
German Bank 1 2024-08-04 12,233 12,233 2023-08-06 2,687 2,687 2,021 2,021
Seal Island 1 2024-08-04 45,930 NA 2023-08-06 1,205 NA 929 NA
German Bank 2 2024-08-18 14,054 11,668 2023-08-20 4,930 4,406 3,282 2,887
Seal Island 2 2024-08-18 6,285 NA 2023-08-20 1,918 NA 897 NA
German Bank 3 2024-09-02 15,499 12,639 2023-09-03 9,959 8,901 8,372 7,660
Seal Island 3 2024-09-02 3,770 NA 2023-09-03 2,063 NA 1,099 NA
German Bank 4 2024-09-15 24,824 21,033 2023-09-13 16,266 13,203 15,011 12,498
Seal Island 4 2024-09-15 1,369 NA 2023-09-13 5,636 NA 4,045 NA
German Bank 5 2024-09-29 10,595 5,068 2023-09-27 15,242 11,360 13,503 9,978
Seal Island 5 2024-09-29 3,134 NA 2023-09-27 53,844 NA 42,269 NA
German Bank 6 2024-10-20 5,151 4,071 2023-10-11 23,614 20,057 26,563 23,390
Seal Island 6 2024-10-20 2,927 NA 2023-10-11 15,261 NA 14,381 NA
German Bank 7 NA NA NA 2023-10-24 11,184 5,502 13,033 6,803
Seal Island 7 NA NA NA 2023-10-24 1,006 NA 1,087 NA
Table 5: Annual Summary Table
Year Ground HSC Estimate HSC Turnover Adjusted DFO Estimate DFO Turnover Adjusted
2023 German Bank 83,882 66,116 81,785 65,237
2023 Seal Island 80,933 NA 64,707 NA
2024 German Bank 82,356 66,712 NA NA
2024 Seal Island 63,415 NA NA NA

Tagging, Plankton, and CTD Data

Summary map

Vessel Tags

Plankton Data

Tow Summary Table

Tow 1
Tow 2
Base Details
Vessel Lady Janice II Lady Janice II
Set Number GB2024-09 GB2024-10
Ground GB GB
Date 20/10/2024 20/10/2024
Wind Direction (km/h) W W
Swell (m) 1 1
Air Temp (c) 13 13
Tow Details
Tow Start 17:54:00 18:08:00
Tow End 18:04:00 18:18:00
Start Lat 43.56950 43.56483
End Lat 43.56500 43.57033
Start Lon -66.35867 -66.36267
End Lon -66.36217 -66.36233
Avg Tow Depth (m) 3.169136 2.298398
Speed 2 2
Heading 208 208
Tide Direction with with
Other Data Collection
Flow Start 979039 4828
Flow End 1004827 42367
No. Revolutions 25788 37539
Distance (m) 693.0009 1008.7855
Volume 2177.062 3169.100
Secchi Disappear (m) 8 8
Secchi Reappear (m) 9 9

Tow Depth Profiles

Plankton tow depth profile #1

Plankton tow depth profile #1

Plankton tow depth profile #2

Plankton tow depth profile #2

The first tow is GB2024-09, which was with the tide and had an average depth of 3.1691356m. The second tow is GB2024-10, which was with the tide and had an average depth of 2.2983982m.

Captured plankton

Captured plankton from the surface tows

Captured plankton from the surface tows

CTD Data

CTD depth profiles for all 2024 German Bank surveys so far.

Sea surface temperatures

Annual average sea surface temperatures (SST) for German Bank.

Vessel Performance

Speed

Average vessel speed was 8.64. This is above the 8 knot requirement; vessels are urged to slow down to prevent backscatter noise from interfering with the acoustic data.

The speed for each transect are rudimentary and are calculated based on distance. If a significant amount of distance is cut, the speed will appear slower.

Distance

No significant distance was cut from the planned lines; vessels covered the planned area well.